The History of the West Nile Virus

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Author: Karen Foster

Where did it come from?

The West Nile virus was first isolated in 1937 in the West Nile district of Uganda. The disease has spread through many parts of Europe and Asia, as well as North and South America.

How did it spread?

We do not know exactly how the virus spread but there are several theories. Most likely the West Nile virus was imported to other countries by a bird or mosquito that was infected by the disease. The virus has been found in over 150 different types of birds including: crows, ravens, blue jays and magpies. Out of the 74 different species of mosquitoes found in all parts of Canada, only ten have been found to carry the West Nile virus.

How is the West Nile virus transmitted?

Mosquitoes become carriers of the West Nile virus after feeding on the blood of birds infected with the virus. The West Nile virus is transmitted to people through the bite of an infected mosquito. Recently, scientists have discovered that people can become infected with the West Nile virus through other ways like blood transfusions and organ/tissue transplants. There is, however, no evidence to suggest that the disease can be contracted by kissing or touching someone who is infected with it.

The West Nile virus poses the greatest risk to those with weakened immune systems or chronic disease and the risk of serious health issues pertaining to the virus increase with age. The risk of being infected with the West Nile virus is greatest during July and August, peak mosquito season. However, it is good to keep in mind that mosquito season lasts from as early as mid April until after the first hard frost usually in October.

Stopping the spread

The very best way to avoid contacting the West Nile virus is by minimizing your exposure to mosquitoes. Other ways to help stop the spread of the West Nile virus include:

- Eliminate mosquito breeding grounds around your home (these include places where standing water can collect such as wading pools, empty flower pots and bird baths)

- Report any dead birds found in your area to the local authorities.

- Use insect repellants that contain DEET and install screens in your windows and doors

- Use mosquito netting when camping

Keep in mind that although the West Nile virus is not likely to disappear any time in the near future, it is important to remember that the risk of contacting the West Nile virus is low and the risk of serious health effects from the disease even lower.